Argon was discovered in 1894 by Lord Rayleigh and Sir William Ramsay in London. Their discovery came about while they were investigating why nitrogen extracted from the air was denser than nitrogen obtained from chemical reactions. They eventually isolated a new component of air, which turned out to be argon, by removing nitrogen, oxygen, carbon dioxide, and water from a sample of atmospheric air. The name “argon” comes from the Greek word ‘argos’, meaning inactive or lazy, reflecting its extremely low reactivity.
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- Symbol: Ar
- Atomic Number: 18
- Atomic Weight: 39.948
- Element Classification: Noble Gas
- Discovered By: Lord Rayleigh and Sir William Ramsay
- Discovery Date: 1894
- Name Origin: Greek: ‘argos’ (inactive, lazy)
- Density(g/cc): 0.0017837 (at 0°C, 101.325 kPa)
- Melting Point: -189.34°C
- Boiling Point: -185.848°C
- Appearance: Colorless, odorless gas
- Atomic Radius(pm): 71
Relation to Other Elements
Argon is a member of the noble gases, group 18 in the periodic table, known for their lack of chemical reactivity due to having full valence electron shells. This makes argon and its noble gas relatives very stable and not prone to forming compounds under normal conditions. Argon is the third most abundant gas in the Earth’s atmosphere and is more than twice as abundant as water vapor.
Natural Occurrence
Argon makes up about 0.934% of the Earth’s atmosphere, making it the most abundant noble gas at ground level. It is primarily obtained through the fractional distillation of liquid air, a process that also yields nitrogen, oxygen, neon, krypton, and xenon. Despite its prevalence in the atmosphere, argon does not play a significant biological role due to its chemical inertness.
Uses
Despite its reactivity, argon has several important industrial and scientific applications:
- Welding: Argon is used as an inert shielding gas in arc welding and metal fabrication, protecting the weld area from atmospheric gases that might cause defects.
- Lighting: It is used in incandescent and fluorescent light bulbs to prevent oxygen from corroding the filament at high temperatures.
- Windows: Argon gas is often used between panes of double-glazed windows to improve thermal insulation because of its low thermal conductivity.
- Scientific Research: In particle physics research, argon is used in ionization detectors and as a medium for neutrino and dark matter experiments.
- Preservation: Due to its inertness, argon is used to displace oxygen and moisture from archival materials or in winemaking to prevent the oxidation of wine.
The discovery of argon expanded the understanding of the atmospheric composition and introduced a new group of elements, the noble gases, into the periodic table. Its unique properties have since made it indispensable in various fields, from welding and lighting to insulation and scientific research.